Double-side display type liquid crystal display device and information appliance

ABSTRACT

A double-side display type liquid crystal display device including a liquid crystal, first and second electrodes for driving the liquid crystal, first and second polarizing means disposed on both sides of the liquid crystal, a front light disposed at the opposite side of the liquid crystal of the first polarizing means, and semitransmission reflecting means disposed at the second polarizing means side of the liquid crystal for passing a part of light from the front light side passing through the liquid crystal. The first polarizing means is optically disposed so as to absorb or transmit light passing through the liquid crystal, and the second polarizing means is optically disposed so as to absorb or transmit light passing through the liquid crystal and then passing through the semitransmission reflecting means.

TECHNICAL FIELD

[0001] The present invention relates to a double-side display typeliquid crystal display device allowing the display image to berecognized from both face and reverse sides, and an informationappliance using the same such as mobile phone, personal digitalassistant (PDA), and wristwatch.

BACKGROUND ART

[0002] Prior Art 1

[0003] A prior art of liquid crystal display device is disclosed, forexample, in Japanese Unexamined Patent Publication No. 326515/1998, inwhich a reflection type liquid crystal display element having areflector is provided, and a front illumination device (front light) isdisposed in front of the reflection type liquid crystal element, andthis reflection type liquid crystal display device is used by puttingoff the front light where a sufficient quantity of ambient light isavailable, for example, in an outdoor place during daytime, and is usedby lighting the front light where sufficient quantity of ambient lightis not obtained.

[0004] Prior Art 2

[0005] Other prior art of liquid crystal display device is asemitransmission reflection type liquid crystal display device formaking reflection type display using external light in a bright place,or transmission type display by backlight in a dark place.

[0006] As proposed, for example, in Japanese Unexamined PatentPublication No. 186362/1998, this semitransmission reflection typeliquid crystal display device has a liquid crystal display panel 100including front side polarizing means, front side transparent plate,transmission type liquid crystal display unit, back side transparentplate, and back side polarizing means as shown in a sectional view ofFIG. 19, in which a backlight 120 composed of a fluorescent lamp, areflector and a triangular light-conducting plate is disposed at theopposite side (back side) of the observation side of this liquid crystaldisplay panel 100, and semitransmission reflecting means 110 composed ofhalf mirror or magic mirror having aluminum or the like affixed to athin transparent film base by vapor deposition, with the film base beingadhered, for example, to the back side of the back side polarizingmeans, is disposed between the backlight 120 and the transmission typeliquid crystal display unit. In FIG. 19, reference numeral 130 denotes alight scattering plate comprising prism plate or diffusion film, 140 acircuit board for driving the liquid crystal display panel 100, and 150a casing accommodating the liquid crystal display panel 100,semitransmission reflecting means 110, backlight 120, scattering plate130 and circuit board 140.

[0007] In the semitransmission reflection type liquid crystal displaydevice having such configuration, in a bright place, external light istaken in as indicated by arrow b, and reflection type display is made bymaking use of the light reflected by the semitransmission reflectingmeans 110, and in a dark place, the backlight 120 is lit, andtransmission type display is made so that the display might berecognized by the light passing through the semitransmission reflectingmeans 110 as indicated by arrow a.

[0008] Prior Art 3

[0009] A different example of semitransmission reflection type liquidcrystal display device is disclosed, for example, in Japanese UnexaminedPatent Publication No. 083494/2001, that is, as shown in a sectionalview of FIG. 20, this semitransmission reflection type liquid crystaldisplay device comprises a transparent first substrate 210; atransparent second substrate 220 disposed oppositely to this firstsubstrate 210, and having a color filter, a transparent electrode and analignment film disposed at the side opposite to the first substrate 210;a liquid crystal 230 interposed between the first substrate 210 andsecond substrate 220; a backlight 240 disposed at the opposite side ofthe liquid crystal 230 of the first substrate 210; a transparent secondinsulation film 250 disposed at the side opposite to the secondsubstrate 220 of the first substrate 210; a reflection electrode 260disposed on the second insulation film 250 and having an opening forpassing light from the backlight 240; a transparent first insulationfilm 270 disposed on the reflection electrode layer 260; and analignment film 280 disposed on the first insulation film 270. In FIG.20, moreover, reference numeral 291 denotes a polarizer, 292 a phasedifference plate, and 293 a sealing material.

[0010] The semitransmission reflection type liquid crystal displaydevice having such configuration can display by changing over betweenreflection type display using the light reflected by the reflectionelectrode 260 by taking in external light, and transmission type displayusing the light passing through the opening in the reflection electrode260 emitted from the backlight 240. Further, in this prior art 3, unlikeprior art 2, there is no transparent electrode between the reflectingmeans and the liquid crystal, and the optical path is shorter in thereflection type display, and therefore the parallax in display image isreduced and the brightness in display image is enhanced.

[0011] Prior Art 4

[0012] A conventional information appliance disclosed, for example, inJapanese Unexamined Patent Publication No. 163638/1996, is a mobilephone comprising, as shown in a perspective view of FIG. 21, a firstmain body having various operation switches, and a second main bodyhaving a liquid crystal display device connected thereto in an openingand closing manner for visibly displaying various kinds of information,and when the second main body is opened, a large screen image display ispossible by the liquid crystal display device, and when the second mainbody is closed, it is reduced to a compact size suited to portable use.In FIG. 21, specifically, reference numeral 301 denotes the first mainbody having various function switches 307 including alphanumerical inputswitches, 302 denotes the second main body having the liquid crystaldisplay device 304 for visibly displaying various kinds of informationand coupled to the first main body 301 in an opening and closing manner,303 denotes a coupling unit of the first main body 301 and second mainbody 302, 305 denotes an antenna, and 306 denotes a button switch forvalidating the inside and outside range display function when the secondmain body 302 is manipulated in closed state. Reference numeral 308denotes a lamp displaying “inside” or “outside”, and specifically theinside range is displayed in a green light and the outside range in ared light, or the range is indicated by lighting or flickering, so thatthe inside and outside can be known at a glance.

[0013] In the information appliance having such configuration, when thebutton switch 306 is manipulated in the closed state of the second mainbody 302, the display lamp 308 displays, so that either “inside” or“outside” of the range can be visually recognized easily.

[0014] The conventional liquid crystal display device is thusconstituted, and whether in reflection type liquid crystal displaydevice or semitransmission reflection type liquid crystal displaydevice, there is only one display panel, and there is even no idea aboutliquid crystal display device capable of displaying in both face andreverse sides.

[0015] In the conventional folding type information appliance, when thesecond main body is closed, although the inside or outside of the rangecan be visually recognized by the lit color, or lighting or flickeringof the display lamp disposed separately from the liquid crystal displaydevice, the display image by the liquid crystal display device cannot berecognized visually in the closed state of the second main body same asin the opened state. As a countermeasure, there might be considered toadd an extra liquid crystal display device exclusive for closed state ofthe second main body, but the number of parts is increased, and hencethe weight, volume and cost are increased.

[0016] Prior Art 5

[0017] Other conventional information appliance is an electronicappliance disclosed, for example, in Japanese Unexamined PatentPublication No. 193956/2000, which is one liquid crystal display devicecomprising, as shown in FIG. 22, a liquid crystal 516 enclosed by a pairof first reflection polarizer 599 and first absorption type polarizer531, and second reflection polarizer 539 and second absorption typepolarizer 519; and a light source light-conducting plate 512 disposed atthe outermost side. In a bright place, reflection type image can be seenby making use of external light b from both sides, and in a dark place,by emitting light a from the light source light-conducting plate 512, abright reflection screen can be observed through the light-conductingplate from the light source light-conducting plate 512 side, or from theopposite side, a bright transmission image can be seen.

[0018] Here, reference numeral 526 denotes a transparent electrode fordriving the liquid crystal 516, and 550 a scattering layer.

[0019] However, in the liquid crystal display device disclosed inJapanese Unexamined Patent Publication No. 193956/2000 and theelectronic appliance using the same, when the surrounding is slightlybright, if the image is observed from the opposite side of the lightsource light-conducting plate 512, since the external light b isinsufficient, the brightness is not enough even in the liquid crystalelement driven by the transparent electrode 526 so that the externallight b is reflected by the first reflection polarizer 599 to bedisplayed in white. At this time, to increase the brightness of theimage, if the light source light-conducting plate 512 is lit to emitlight a, the polarized light a after passing through the firstreflection polarizer 599 and first absorption type polarizer 531 isreflected by the second reflection polarizer 539 in this liquid crystalelement, and cannot pass, so that the brightness cannot be increased.

[0020] To the contrary, in the case of the liquid crystal display devicebeing driven so that the external light b passes through the firstreflection polarizer 599 and is not reflected to be displayed in black,the polarized light a passing through the first reflection polarizer 599and first absorption type polarizer 531 is not reflected by the secondreflection polarizer 539, but passes through the same, and hence theblack display becomes bright and the contrast is lowered, thereby thedisplay quality deteriorates.

[0021] The present invention is made to solve the problems of theseprior arts, and it is a first object thereof to present a double-sidedisplay type liquid crystal display device capable of displaying abright image of excellent display quality on both face and reversesides.

[0022] It is a second object thereof to present an information applianceallowing to recognize a display image by one liquid crystal displaydevice in both opened state and closed state of a second main body,without adding a new image display device.

DISCLOSURE OF INVENTION

[0023] A double-side display type liquid crystal display device of thepresent invention includes a liquid crystal, first and second electrodesfor driving the liquid crystal, first and second polarizing meansdisposed on both sides of the liquid crystal, a front light disposed atthe opposite side of the liquid crystal of the first polarizing means,and semitransmission reflecting means disposed at the second polarizingmeans side of the liquid crystal for passing a part of light from thefront light side passing through the liquid crystal, in which the firstpolarizing means is optically disposed so as to absorb or transmit lightpassing through the liquid crystal, and the second polarizing means isoptically disposed so as to absorb or transmit light passing through theliquid crystal and then passing through the semitransmission reflectingmeans.

[0024] Moreover, the semitransmission reflecting means is a reflectordisposed between the liquid crystal and the second polarizing means, andhaving a transmission window for passing a part of light from the frontlight side passing through the liquid crystal.

[0025] Moreover, the first and second electrodes are transparentelectrodes disposed between the liquid crystal and first polarizingmeans and the liquid crystal and second polarizing means respectively,and the reflector having a transmission window is disposed at theopposite side of the liquid crystal of the second electrode.

[0026] Moreover, the semitransmission reflecting means is a reflectionpolarizer disposed between the liquid crystal and the second polarizingmeans, for reflecting light having a specified polarizing characteristicand passing all other light.

[0027] Further, the device includes first and second glass substratesholding the liquid crystal therebetween and disposed between the liquidcrystal and the first and second polarizing means respectively, and acolor filter at either liquid crystal side of the first or second glasssubstrate; the reflection polarizer is adhered to the opposite side ofthe liquid crystal of the second substrate; and the thickness of thesecond substrate is 5 times or less of the narrowest width of the colorfilter.

[0028] Further, the device includes a metal wiring electricallyconnected to the first electrode or second electrode, and a firstquarter λ phase difference plate is disposed between the metal wiringand first polarizing means when the metal wiring is located between theliquid crystal and the first polarizing means, or between the metalwiring and reflection polarizer when the metal wiring is located betweenthe liquid crystal and reflection polarizer.

[0029] Further, the device includes a metal wiring electricallyconnected to the first electrode or second electrode, and a lowreflection layer of lower reflectivity of light than that of the metalwiring disposed at the opposite side of the liquid crystal of the metalwiring, the low reflection layer being optically disposed closely in ashape after the metal wiring.

[0030] An information appliance of the present invention includes afirst main body having various operation switches, and a second mainbody having display means for visually displaying various kinds ofinformation, being coupled to the first main body in an opening andclosing manner. The display means is a double-side display type liquidcrystal display device including a liquid crystal, first and secondelectrodes for driving the liquid crystal, first and second polarizingmeans disposed on both sides of the liquid crystal, a front lightdisposed at the opposite side of the liquid crystal of the firstpolarizing means, and semitransmission reflecting means disposed at thesecond polarizing means side of the liquid crystal for passing a part oflight from the front light side passing through the liquid crystal;windows are disposed at the inner side of the casing and at the outerside thereof when the second main body is closed; the surface of thefront light side of the double-side display type liquid crystal displaydevice is disposed at one window; and the surface of the secondpolarizing means side of the double-side display type liquid crystaldisplay device is disposed at the other window.

[0031] The surface of the double-side display type liquid crystaldisplay device on the front light side is disposed at the windowprovided at the outer side of the second main body, and the surface ofthe double-side display type liquid crystal display device on the secondpolarizing means side is disposed at the window provided at the innerside.

[0032] The appliance further includes opening/closing judging means forjudging the opening or closing of the second main body, and a frontlight lighting switch which cooperates with the opening/closing judgingmeans for lighting the front light when the main body is judged to beopened.

[0033] The appliance further includes writing direction inverting meansfor inverting the writing direction of display image data into eachpixel of the double-side display type liquid crystal display device invertical or lateral direction.

[0034] The appliance further includes data converting means forconverting the data of display image into data inverted in vertical orlateral direction.

[0035] The appliance further includes data converting means forconverting the gradation of the data of display image.

[0036] The appliance further includes a second quarter % phasedifference plate disposed at the opposite side of the liquid crystal ofthe second polarizing means of the double-side display type liquidcrystal display device.

BRIEF DESCRIPTION OF DRAWINGS

[0037]FIG. 1 is a diagram explaining a double-side display type liquidcrystal display device and an information appliance using the sameaccording to Embodiment 1 of the present invention;

[0038]FIG. 2 is a diagram explaining the double-side display type liquidcrystal display device and the information appliance using the sameaccording to Embodiment 1 of the present invention;

[0039]FIG. 3 is a diagram explaining the double-side display type liquidcrystal display device and the information appliance using the sameaccording to Embodiment 1 of the present invention;

[0040]FIG. 4 is a diagram explaining the double-side display type liquidcrystal display device and the information appliance using the sameaccording to Embodiment 1 of the present invention;

[0041]FIG. 5 is a diagram explaining the double-side display type liquidcrystal display device and the information appliance using the sameaccording to Embodiment 1 of the present invention;

[0042]FIG. 6 is a diagram explaining a double-side display type liquidcrystal display device and an information appliance using the sameaccording to Embodiment 2 of the present invention;

[0043]FIG. 7 is a diagram explaining a double-side display type liquidcrystal display device and an information appliance using the sameaccording to Embodiment 3 of the present invention;

[0044]FIG. 8 is a diagram explaining the double-side display type liquidcrystal display device and the information appliance using the sameaccording to Embodiment 3 of the present invention,

[0045]FIG. 9 is a diagram explaining the double-side display type liquidcrystal display device and the information appliance using the sameaccording to Embodiment 3 of the present invention;

[0046]FIG. 10 is a diagram explaining the double-side display typeliquid crystal display device and the information appliance using thesame according to Embodiment 3 of the present invention;

[0047]FIG. 11 is a diagram explaining a double-side display type liquidcrystal display device and an information appliance using the sameaccording to Embodiment 4 of the present invention;

[0048]FIG. 12 is a diagram explaining the double-side display typeliquid crystal display device and the information appliance using thesame according to Embodiment 4 of the present invention;

[0049]FIG. 13 is a diagram explaining a double-side display type liquidcrystal display device and an information appliance using the sameaccording to Embodiment 5 of the present invention;

[0050]FIG. 14 is a diagram explaining the double-side display typeliquid crystal display device and the information appliance using thesame according to Embodiment 5 of the present invention;

[0051]FIG. 15 is a diagram explaining a double-side display type liquidcrystal display device and an information appliance using the sameaccording to Embodiment 6 of the present invention;

[0052]FIG. 16 is a diagram explaining a double-side display type liquidcrystal display device and an information appliance using the sameaccording to Embodiment 7 of the present invention;

[0053]FIG. 17 is a diagram explaining the double-side display typeliquid crystal display device and the information appliance using thesame according to Embodiment 7 of the present invention;

[0054]FIG. 18 is a diagram explaining the double-side display typeliquid crystal display device and the information appliance using thesame according to Embodiment 7 of the present invention;

[0055]FIG. 19 is a diagram explaining a semitransmission reflection typeliquid crystal display device in Prior Art 2;

[0056]FIG. 20 is a diagram explaining a semitransmission reflection typeliquid crystal display device in Prior Art 3;

[0057]FIG. 21 is a diagram explaining an information appliance in PriorArt 4; and

[0058]FIG. 22 is a diagram explaining a double-side display type liquidcrystal display device in Prior Art 5.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1

[0059] An example of a foldable mobile phone according to Embodiment 1of the present invention is explained below with reference to thedrawings.

[0060]FIG. 1 to FIG. 5 are diagrams explaining a double-side displaytype liquid crystal display device and an information appliance usingthe same according to Embodiment 1 of the present invention, and morespecifically FIG. 1 is a partially cut-away appearance view showing afolded state (closed state of second main body) of a foldable mobilephone as an information appliance, FIG. 2 is a partially cut-awayappearance view showing an opened state of the second main body, FIG. 3is a sectional view magnifying essential parts in FIG. 1, FIG. 4 is adiagram explaining the writing direction of display image data into eachpixel of the double-side display type liquid crystal display device inthe closed state of the second main body, and FIG. 5 is a diagramexplaining the writing direction of display image data into each pixelof the double-side display type liquid crystal display device in theopened state of the second main body.

[0061] In FIG. 1 and FIG. 2, reference numeral 1 denotes a first mainbody having various operation switches 2, 3 a second main body having adouble-side display type liquid crystal display device for visuallydisplaying various kinds of information, 4 a hinge for coupling thesecond main body 3 to the first main body 1 in an opening and closingmanner, and 5 a transparent cover. A double-side display type liquidcrystal display device 10 is described later in detail with the use ofFIG. 3.

[0062] A foldable mobile phone of the Embodiment comprises a first mainbody 1 having various function switches 2 including alphanumeric inputswitches, and a second main body 3 having a double-side display typeliquid crystal display device 10 for visibly displaying various kinds ofinformation as display means. The second main body 3 is coupled to thefirst main body 1 by a hinge 4 so as to be openable and closable.Openings (windows) are provided at both the outer side coming to theoutside and the inner side coming to the inside when the second mainbody 3 is closed, and a transparent cover 5 is provided at the outerside opening (the window provided at the outer side) so as to disposethe front light side surface of the double-side display type liquidcrystal display device 10, and the surface of the double-side displaytype liquid crystal display device 10 on the second polarizing meansside is provided at the inner side opening (the window provided at theinner side), thereby composing a display unit.

[0063] In FIG. 3, reference numeral 6 denotes a front light having alight source 11 composed of light-emitting diode (LED) and alight-conducting plate 12, 12 a a reflection prism provided in thelight-conducting plate 12, 13 a color filter (CF) side polarizercorresponding to first polarizing means, 14 a CF side phase differenceplate, 15 a CF side glass substrate corresponding to transparent firstsubstrate, 16 a liquid crystal layer, 17 a thin film transistor (TFT)array side glass substrate corresponding to transparent secondsubstrate, 18 a TFT array side phase difference plate, 19 a TFT arrayside polarizer corresponding to second polarizing means, 20 a gate TFT,21 a reflection electrode having a transmission window 22, 23 a TFTarray side transparent electrode corresponding to second electrode, 25 aCF, 26 a CF side transparent electrode corresponding to first electrode,27 a transparent insulation film, and 40 a quarter λ phase differenceplate (second quarter λ phase difference plate). Reference numeral 101 adenotes a liquid crystal display panel having the liquid crystal 16 andfirst and second electrodes 26 and 23 for driving the liquid crystal 16,and in this Embodiment it further includes the reflection electrode 21having the transmission window 22 (corresponding to the reflector havingthe transmission window for passing a part of light from the front light6 side passing through the liquid crystal 16), and this is asemitransmission type liquid crystal display panel for passing a part oflight passing through the liquid crystal 16 and reflecting theremainder. The liquid crystal 16 is driven by the first electrode 26 andsecond electrode 23, and the quantity of birefringence of the liquidcrystal 16 is controlled.

[0064] In this Embodiment, a pixel electrode 24 is composed of thereflection electrode 21 having the transmission window 22 and the TFTarray side transparent electrode 23, and the pixel electrode 24 arealigned in an array on the TFT array side glass substrate 17.

[0065] The double-side display type liquid crystal display device 10 ofthe Embodiment mainly comprises the following members. That is, itcomprises a transparent first substrate 15 having a transparent firstelectrode 26 formed thereon, a transparent second substrate 17 having atransparent second electrode 23 formed thereon and disposed oppositelyto the first substrate 15, a liquid crystal 16 held between the firstsubstrate 15 and second substrate 17, first polarizing means 13 andsecond polarizing means 19 disposed respectively at the opposite side ofthe liquid crystal 16 of the first substrate 15 and second substrate 17,semitransmission reflection means 21, 22 disposed between the liquidcrystal 16 and second polarizing means 19 for passing a part of lightpassing through the first substrate 15 and liquid crystal 16, and afront light 6 disposed at the opposite side of the first substrate 15 ofthe first polarizing means 13.

[0066] More specifically, the double-side display type liquid crystaldisplay device 10 of the Embodiment comprises a front light 6 composedof a light source 11 and a front light light-conducting plate 12, a CFside glass substrate 15 having a CF 25 and a CF side transparentelectrode 26, a TFT array side glass substrate 17, a liquid crystal 16of, for example, TN liquid crystal enclosed by these two glasssubstrates 15, 17, a reflection electrode 21 having a transmissionwindow 22 for passing a part of light backward, a TFT array sidetransparent electrode 23 to which a voltage is applied through a gateTFT 20 same as the reflection electrode 21, a phase difference plate 18,a second polarizer (TFT array side polarizer 19) and a quarter λ phasedifference plate 40 sequentially adhered to the TFT array side glasssubstrate 17, and a phase difference plate 14 and a first polarizer (CFside polarizer 13) sequentially adhered to the color filter side glasssubstrate 15.

[0067] When the second main body 3 is closed, the inner side of thefirst main body 1 is opposite to the quarter λ phase difference plate40.

[0068] Referring now to FIG. 1, FIG. 3 and FIG. 4, there is explainedthe operation of the double-side display type liquid crystal displaydevice of the Embodiment and the foldable mobile phone using the samewhen its second main body 3 is closed, relating to a case of lighting ofthe front light 6. As shown in FIG. 1, when the second main body 3 isclosed, the surface of the front light 6 side of the double-side displaytype liquid crystal display device 10 is shown to the user side.

[0069] In FIG. 3, as indicated by arrow L, the light emitted from thelight source 11 spreads by diffusing and propagating through thelight-conducting plate 12, and is radiated to the CF side polarizer 13as indicated by arrow Li by a reflection prism 12 a provided in thelight-conducting plate 12. The radiated light enters the CF sidepolarizer 13 to be a straight polarized light, and passes through the CFside phase difference plate 14, first substrate 15, liquid crystal 16,and TFT array side transparent electrode 23, and reaches the reflectionelectrode 21. Further, as indicated by arrow Lr, it is reflected by thereflection electrode 21 to be a reflected light, which passes againthrough the liquid crystal 16, first substrate 15, CF side phasedifference plate 14, CF side polarizer 13, front light 6, andtransparent cover 5, and is visually recognized by the user at the frontlight 6 side of the double-side display type liquid crystal displaydevice 10 (reflection type display).

[0070] At this time, depending on the quantity of birefringence of theliquid crystal 16 layer determined by the electric field between thevoltage applied to the pixel electrode 24 and the CF side transparentelectrode 26, and on the quantity of birefringence of the CF side phasedifference plate 14, the transmissivity of the reflected light indicatedby arrow Lr when passing through the CF side polarizer 13 varies in arange of 0 to 1, and accordingly by setting the voltage applied to thepixel electrode 24, in every pixel, depending on the image, the imagedisplay is realized. Usually it is set to heighten the transmissivitywhen the electric field is 0, and lower the transmissivity to 0 when theelectric field becomes stronger.

[0071]FIG. 4 is a diagram explaining the writing direction of the imagedisplay data when the second main body is closed into each pixel of thedouble-side display type liquid crystal display device, showing thedisplay image of the double-side display type liquid crystal displaydevice 10 seen from the CF side glass substrate (first substrate) 15side. In FIG. 4, reference numeral 51 denotes a gate line, 52 a gatedriver, 54 a source line, and 55 a source driver. A plurality of gatelines 51 and source lines 54 are disposed each in the vertical directionand lateral direction, and a pixel composed of gate TFT 20 and pixelelectrode 24 is disposed at each intersection. Reference numeral 61denotes an image signal generating device, 62 opening/closing judgingmeans for judging the opening or closing of the second main body 3, and63 writing direction inverting means for inverting the writing directionof display image data into each pixel of the double-side display typeliquid crystal display device in the vertical direction, correspondingto the opening or closing of the second main body 3, in collaborationwith the opening/closing judging means 62.

[0072] The image signal generating device 61 is composed of, forexample, frame memory and CPU, and sequentially generates image signalsto be written into each pixel of the double-side display type liquidcrystal display device and writing timing signals.

[0073] The opening/closing judging means 62 is composed of, for example,cantilever and switch, and judges whether the second main body 3 isclosed or open by detecting, for example, the angle of the hinge 4.

[0074] The writing direction inverting means 63 is composed of, forexample, electronic circuit, and controls, for example, the gate driver52, changes over the start gate and shift direction of the shiftregister, and inverts the selection sequence of gate lines 51, such asfrom corner A to C when the second main body 3 is closed, or from cornerC to A when the second main body 3 is open, thereby inverting thewriting direction of display image data into each pixel of the liquidcrystal display device in the vertical direction without changing thesequence of the image signal outputs from the image signal generatingdevice 61 and the writing timing.

[0075] The opening/closing judging means 62 for judging the opening orclosing of the second main body 3 judges that the second main body 3 isclosed. In consequence, the writing direction inverting means 63 setsthe selection sequence of the gate lines 51 to shift from the gate lineof the corner A side to the direction of C side. Therefore, the gatelines 51 for applying gate ON voltage are sequentially changed fromcorner A to direction of C among gate lines 51 by the gate driver 52,and at the same time, in the selected state of the gate line, thecorresponding image data sent from the image signal generating device bythe source driver 55 is changed over to the gradation voltage, which isapplied in batch to all source lines 54, and it is applied to the pixelelectrode 24 of each element on the selected gate line. By repeatingthis operation to the gate line of corner C, the image can be formed ina line sequence system from corner A to C, so that the image of thereflection mode can be visually recognized through the cover window 5from the front light 6 side of the double-side display type liquidcrystal display device 10.

[0076] So far, an example of lighting of the front light 6 is explained,but it is the same when using external light (indicated by arrow Lo) byputting out the front light 6.

[0077] Therefore, a bright image can be displayed by using both thelight of the front light 6 and external light (arrow Lo) at the sametime.

[0078] Here, effects of transmission light (arrow Ld) when the secondmain body 3 is closed are studied. The reflection electrode 21 has atransmission window 22, and a part of the front light radiated light(arrow Li) reaching the reflection electrode 21 leaks to the oppositeside through the transmission window 22 to be transmission light (arrowLd). This transmission light (arrow Ld) is reflected by the surface ofthe first main body 1 to be scattered reflected light (arrow Ls). Thisscattered reflected light (arrow Ls) passes again through thedouble-side display type liquid crystal display device 10, and when itleaks to the direction of the transparent cover 5, it induces coloroozing, contrast decline or contour blurring. In this Embodiment,however, the quarter λ phase difference plate 40 is provided at theoutside of the TFT array side polarizer 19, and the scattered reflectedlight (arrow Ls), after leaving the TFT array side polarizer 19, passesthrough the quarter λ phase difference plate 40 twice, and hence itbecomes a straight polarized light orthogonal to the axis ofpolarization of the TFT array side polarizer 19 to be absorbed by theTFT array side polarizer 19. As a result, such adverse effects asmentioned above are suppressed.

[0079] Referring next to FIG. 2, FIG. 3 and FIG. 5, there is explainedthe operation of the double-side display type liquid crystal displaydevice and the foldable mobile phone using the same according to theEmbodiment when its second main body 3 is opened. As shown in FIG. 2,when the second main body 3 is opened in the vertical direction, theopposite side (reverse side) of the front light 6 of the double-sidedisplay type liquid crystal display device 10 is shown to the user side.

[0080] The foldable mobile phone according to the Embodiment has a frontlight lighting switch (not shown) for lighting the front light 6 whenthe opening/closing judging means 62 judges that the second main body 3is open, and therefore when the opening/closing judging means 62 judgesthat the second main body 3 is open by detecting, for example, the angleof the hinge 4, the front light 6 is lit up automatically.

[0081] The light emitted from the light source 11 of the front light 6spreads by diffusing and propagating through the front lightlight-conducting plate 12, and is radiated to the CF side polarizer 13side by a reflection prism 12 a provided in the light-conducting plate12. The radiated light enters the CF side polarizer 13 to be a straightpolarized light as indicated by arrow Li, and passes through the CF sidephase difference plate 14, first substrate 15, liquid crystal 16, TFTarray side transparent electrode 23 or the like, and reaches thereflection electrode 21, which is same as the operation in the case ofclosing of the second main body 3. Further, as indicated by arrow Ld, itpasses through the transmission window 22 of the reflection electrode21, and transmission light leaks to the reverse side. This transmissionlight passes through the TFT array side phase difference plate 18, TFTarray side polarizer 19 or the like, and further passes through thequarter λ phase difference plate 40, to be visually recognized by theuser at the reverse side of the double-side display type liquid crystaldisplay device 10 (transmission type display).

[0082] At this time, depending on the quantity of birefringence of theliquid crystal 16 layer determined by the electric field between thevoltage applied to the pixel electrode 24 and the CF side transparentelectrode 26, and on the quantity of birefringence of the CF side phasedifference plate 14 and the TFT array side phase difference plate 18,the transmissivity of the transmission light indicated by arrow Ld whenpassing through the TFT array side polarizer 19 varies in a range of 0to 1, and accordingly by setting the voltage applied to the pixelelectrode 24, in every pixel, depending on the image, the image displayby so-called transmission mode is realized. Generally, same as in thereflection mode, the quantity of birefringence of the TFT array sidephase difference plate 18 is set so as to minimize also thetransmissivity of the transmission light in the transmission mode in theTFT array side polarizer 19, at a voltage of minimum transmissivity ofthe reflected light in the reflection mode in the CF side polarizer 13.

[0083] At this time, in the case of a bright surrounding, ambientexternal light (arrow Lo) enters through the front lightlight-conducting plate 12, so that a bright image can be seen byutilizing both the external light (arrow Lo) and light (arrow L) of thelight source 11 at the same time. Further, when the external light(arrow Lo) enters from the observer side, that is, from the secondpolarizer side (from the reverse side), the external light which entersthe second polarizer, that is, the TFT array side polarizer 19 to be astraight polarized light passes through the transmission window 22 ofthe reflection electrode 21 and further passes through the liquidcrystal layer to reach the first polarizer, that is, the color filterside polarizer 13. However, regardless of the driving state of theliquid crystal 16, since the light is almost completely absorbed ortransmitted in this color filter side polarizer 13, almost no reflectedlight comes out. Hence, the contrast is not lowered.

[0084] At this time, though the reflection from the color filter sidepolarizer 13 which is the first polarizer is desired to be smallerbecause a high contrast is obtained, if there is almost no reflection,it is a level allowed as a picture quality in actual use. For example,to realize a contrast of 10 or more, preferably, at least more than 90%of the light reaching the color filter side polarizer 13 which is thefirst polarizer after passing through the transmission window 22 of thereflection electrode 21 and passing through the liquid crystal 16 layershould be adsorbed or transmitted in this color filter side polarizer 13regardless of the driving state of the liquid crystal 16, while thereflected light should be within 10%.

[0085]FIG. 5 is a diagram explaining the writing direction of thedisplay image when the second main body 3 is opened into each pixel ofthe double-side display type liquid crystal display device, showing thedisplay image of the double-side display type liquid crystal displaydevice 10 seen from the TFT array side glass substrate (secondsubstrate) 17 side. As compared with the closed state of the second mainbody 3 shown in FIG. 4, the vertical direction is inverted, and cornersA and C, and corners B and D are exchanged from each other.

[0086] The opening/closing judging means 62 judges that the second mainbody 3 is open by detecting, for example, the angle of the hinge 4. Inconsequence, the writing direction inverting means 63 inverts theselection sequence of the gate line 51 automatically from the sequencefrom gate at corner A side to C side direction to the sequence fromcorner C side gate to A side gate direction. Therefore, when selectingthe gate line for applying the gate ON voltage among the gate lines 51by the gate driver 52, the gate lines are selected sequentially from thecorner C, not from the corner A, and in the selected state of the gateline simultaneously, each gradation voltage is applied in batch to allsource lines 54, and the gate TFT 20 of the pixel at the intersection isturned on to apply the gradation voltage to the pixel electrode 24. Byrepeating this operation to the gate line of corner A, the image can beformed in a line sequence system from corner C to A, so that the imagein the correct direction of the transmission mode can be visuallyrecognized from the opposite side (reverse side) of the front light 6 ofthe double-side display type liquid crystal display device 10.Accordingly, the user can visually recognize the image in the correctdirection, if the second main body 3 is opened in the upper direction,without changing the holding position (while holding the first main body1) from the closed state of the second main body 3.

[0087] As described above, the Embodiment comprises the liquid crystal16, first and second polarizing means 13 and 19 disposed on both sidesof the liquid crystal 16, transparent first and second electrodes 26 and23 disposed between the liquid crystal 16 and the first and secondpolarizing means 13 and 19 respectively, for controlling the quantity ofbirefringence by driving the liquid crystal, semitransmission reflectingmeans 21 disposed between the liquid crystal 16 and second polarizingmeans 13 for passing a part of the light passing through the liquidcrystal, and front light 6 disposed at the opposite side of the liquidcrystal 16 of the first polarizing means 13, in which thesemitransmission reflecting means is the reflection electrode 21disposed at the opposite side of the liquid crystal 16 of the secondelectrode 23, and having the transmission window 22 for passing a partof the light passing through the first electrode 26, liquid crystal 16,and second electrode 23. Therefore, the light reaching the reflectionelectrode 21 from the front light 6 side after passing through the firstpolarizing means 13, first electrode 26, liquid crystal 16, and secondelectrode 23 partly passes through the transmission window 22 of thereflection electrode 21 to reach the second polarizing means 19, whilethe remainder is reflected by the reflection electrode 21 to reach thefirst polarizing means 13, so that the display image is visible fromboth sides of the first polarizing means 13 side and second polarizingmeans 19 side. Further, in the reflection type display by the lightreflected by the reflection electrode 21, since the second substrate 17is not present between the reflecting means (reflection electrode 21)and the first polarizing means 13, the optical path is shorter ascompared with the case of presence of the second substrate 17, so thatthe parallax in the display image is reduced.

[0088] Though the above explanation is made in the case where the secondmain body 3 opens and closes in the vertical direction, even whenopening and closing in the lateral direction, similar effects areobtained by inverting the writing direction of display image data to thelateral direction into each pixel of the double-side display type liquidcrystal display device by the writing direction inverting means 63.

[0089] The reflection electrode 21 is usually made of a conductive metalsuch as aluminum or silver, but it might be also made of a transparentelectrode in a structure having an insulation film or metal film forreflecting the light at a high reflectivity by closely and opticallycontacting with the opposite side of the liquid crystal 16.

[0090] In the foregoing explanation, the first electrode and firstpolarizer at the front light side of the liquid crystal 16 layer are atthe color filter side, and the second electrode and second polarizer areat the TFT array side, and the reflection electrode 21 having thetransmission window 22 is provided at the opposite side of the liquidcrystal 16 of the second electrode, that is, the TFT array sidetransparent electrode 23, but to the contrary, the same effects areobtained if the first electrode and first polarizer are at the TFT arrayside, the second electrode and second polarizer are at the color filter(CF) side, and the reflection electrode 21 having the transmissionwindow 22 is provided at the opposite side of the liquid crystal 16 ofthe CF side transparent electrode 26.

[0091] In the foldable mobile phone of the Embodiment described above,in the closed state of the second main body 3, the image (the imageviewed from the front light 6 side of the double-side display typeliquid crystal display device 10) displayed in the double-side displaytype liquid crystal display device 10 includes, when receiving, thesender's name, sender's portrait, mail message, i-mode (registeredtrademark) reception area map, home page (HP), and others, and, whilewaiting, the waiting screen of the mobile phone shows, for example, theantenna showing the intensity of radio wave, battery level, calendar,time, illustration, portrait, game, i-mode reception area map, HP,decorative pattern, and decorative illumination.

[0092] In the open state of the second main body 3, the image (the imageviewed from the TFT array side polarizer 19 side of the double-sidedisplay type liquid crystal display device 10) displayed in thedouble-side display type liquid crystal display device 10 includes, whenreceiving, the sender's name, sender's portrait, mail message, andothers, and, while waiting, the waiting screen of the mobile phoneshows, for example, the antenna showing the intensity of radio wave,battery level, calendar, time, illustration, portrait, game, and mailmessage writing screen.

[0093] In the foregoing Embodiment, the semitransparent reflecting meansfor passing a part of the light passing through the first substrate 15and liquid crystal 16 is the reflection electrode 21 formed at theliquid crystal layer side of the second substrate 17, and has thetransmission window 22 for passing a part of the light passing throughthe first substrate 15, first electrode 26, liquid crystal 16 and secondelectrode 23. The present invention is not, however, limited to this,and instead of the reflection electrode 21 having the transmissionwindow 22, the reflector having the transmission window might be formed,for example, by using an aluminum vapor deposition mirror film havingmultiple fine transmission windows, and this reflector havingtransmission windows might be adhered between the second glasssubstrate, that is, the TFT array side glass substrate 17 and the TFTarray side phase difference plate 18.

[0094] Further, as described in Prior Art 2, for example, using a filmof half mirror or magic mirror with aluminum formed on a thintransparent film base by vapor deposition, the film base might beadhered to the quarter λ phase difference plate 40 of the TFT array sidepolarizer 19.

Embodiment 2

[0095]FIG. 6 is a diagram explaining a double-side display type liquidcrystal display device and an information appliance using the sameaccording to Embodiment 2 of the present invention, and morespecifically it is a diagram explaining shuffling of data of displayimage. Other configuration is same as in Embodiment 1.

[0096] In FIG. 6, reference numeral 64 denotes data converting means forconverting the data of display image by shuffling upside downcorresponding to the opening/closing position of the second main body 3,in collaboration with the opening/closing judging device 62. The dataconverting means 64 is specifically composed of, for example, framememory and CPU, and the image signal (image data) generated in an imagesignal generating device 61 is once stored, and converted into data byinverting the display image upside down, and sent to a source driver 55.

[0097] In a foldable mobile phone of the Embodiment having suchconfiguration, the sequence of gate selection of a double-side displaytype liquid crystal display device 10 is the same regardless of openingor closing of a second main body 3, and corresponding to the open orclosed state of the second main body 3 detected by an opening/closingjudging device 62, the image data to be displayed is converted byshuffling in the vertical direction automatically by the data convertingmeans 64, and sent into the source driver 55 of the double-side displaytype liquid crystal display device 10. Therefore, the user can view theimage in correct direction if the second main body 3 is opened in theupper direction without having to change the holding position in theclosed state of the second main body (while holding the first main body1).

[0098] In the foregoing Embodiments, the second main body is opened andclosed in the vertical direction, but same effects are obtained ifopened and closed in the lateral direction by converting the data byinverting in the lateral direction by the data converting means 64.

Embodiment 3

[0099]FIG. 7 to FIG. 10 are diagrams explaining a double-side displaytype liquid crystal display device and an information appliance usingthe same according to Embodiment 3 of the present invention, and morespecifically FIG. 7 is a magnified sectional view of essential parts ofa foldable mobile phone as an information appliance in a folded state(second main body is closed), FIG. 8 is an explanatory diagram of anexample of the direction of polarization for each light shown in FIG. 7,FIG. 9 is a magnified sectional view of essential parts of the secondmain body in an opened state, and FIG. 10 is an explanatory diagram ofan example of the direction of polarization for each light shown in FIG.9.

[0100] In the foregoing Embodiment 1, the semitransmission reflectingmeans which passes a part of the light passing through the liquidcrystal 16 is composed of the reflection electrode 23 having thetransmission window 22, but in this Embodiment it is composed of areflection polarizer for reflecting the light having a specifiedpolarizing characteristic, and almost passing other light (reflectingthe light straightly polarized in a specified direction and passing thelight straightly polarized in a direction perpendicular to the specifieddirection).

[0101] In FIG. 7 to FIG. 10, reference numeral 58 denotes a TFT arrayside reflection polarizer disposed between a liquid crystal 16 andsecond polarizing means (TFT array side polarizer 19) for reflecting thelight straightly polarized in a specified direction and passing thelight straightly polarized in a direction perpendicular to the specifieddirection, and in this Embodiment it is disposed between a TFT arrayside glass substrate 17 and TFT array side polarizer 19. The TFT arrayside reflection polarizer 58 is composed of, for example, DBEF (DoubleBrightness Enhanced Film, a trade name of SUMITOMO 3M LIMITED).Reference numeral 204 denotes a metal wiring for applying a voltage to asecond electrode (TFT array side transparent electrode 23). Referencenumeral 180 denotes a first quarter λ phase difference plate, and it isdisposed between the metal wiring 204 and reflection polarizer 58 inthis Embodiment. Reference numeral 140 denotes a third quarter λ phasedifference plate, and it is disposed between a color filer (CF) sideglass substrate 15 and first polarizing means (CF side polarizer 13) inthis Embodiment. Reference numeral 101 b denotes a liquid crystaldisplay panel having a liquid crystal 16 and first and second electrodes26 and 23 for driving the liquid crystal 16, and in this Embodiment thefirst and second electrodes 26 and 23 are transparent electrodes nothaving reflection function, and this is a total transmission type liquidcrystal display panel for passing all light entering the liquid crystal16.

[0102] In the foregoing Embodiment 1, a pixel electrode is composed ofreflection electrode 21 and TFT array side transparent electrode 23, butin this Embodiment a pixel electrode is composed of TFT array sidetransparent electrode 23, and pixel electrodes are arranged in an arrayon the TFT array side glass substrate 17.

[0103] A foldable mobile phone according to the Embodiment is same as inEmbodiment 1, except for the structure of double-side display typeliquid crystal display device 10. That is, it comprises a first mainbody 1 having various function switches 2 including alphanumeric inputswitches, and a second main body 3 having a double-side display typeliquid crystal display device 10 visibly displaying various kinds ofinformation as display means and being coupled to the first main body 1by a hinge 4 in an opening and closing manner. Openings (windows) areprovided at both outer side coming to the outside and inner side comingto the inside when the second main body 3 is closed, and a transparentcover 5 is provided at the outer side opening (the window provided atthe outer side) so as to dispose the front light side surface of thedouble-side display type liquid crystal display device 10, and thesurface of the second polarizing means side of the double-side displaytype liquid crystal display device 10 is provided at the inner sideopening (the window provided at the inner side), thereby composing adisplay unit.

[0104] Hereinafter, mainly, the different points from Embodiment 1 aredescribed. The double-side display type liquid crystal display deviceaccording to the Embodiment comprises a front light 6 composed of alight source 11 and a front light guide 12, a CF side glass substrate 15having a CF 25 and a CF side transparent electrode 26, a TFT array sideglass substrate 17, a liquid crystal layer 16 of, for example, TN liquidcrystal held between these two glass substrates 15 and 17, and a TFTarray side transparent electrode 23 to which a voltage is appliedthrough a gate TFT 20, and further a first quarter λ phase differenceplate (TFT array side quarter λ phase difference plate 180), areflection polarizer 58, a second polarizer (TFT array side polarizer19), and second quarter λ phase difference plate 40 are sequentiallyadhered on the TFT array side glass substrate 17, and a third quarter λphase difference plate (CF side quarter λ phase difference plate 140)and a first polarizer (CF side polarizer 13) are sequentially adhered onthe CF side glass substrate 15.

[0105] Referring then to FIG. 7 to FIG. 10, the operation of thedouble-side display type liquid crystal display device according to theEmbodiment is explained on the basis of an example of lighting of thefront light 6.

[0106] As indicated by arrow L, the light emitted from the light source11 spreads by diffusing and propagating through the light-conductingplate 12, and is radiated by the reflection prism 12 a provided in thelight-conducting plate 12 to the CF side polarizer 13 side as indicatedby arrow Li. The radiated light is straightly polarized by the CF sidepolarizer 13 (in FIG. 8 and FIG. 10, a straightly polarized light in thelateral direction), and passes through the CF side quarter λ phasedifference plate 140, and enters the total transmission type liquidcrystal display panel 101 b. Further, passing through the TFT array sidequarter λ phase difference plate 180, it reaches the TFT array sidepolarization reflector 58.

[0107] In the total transmission type liquid crystal display panel 101b, when voltage is not applied between the CF side transmissionelectrode 26 and TFT array side transparent electrode 23, the directionof polarization is rotated by 180 degrees by the quantity ofbirefringence (retardation) of the liquid crystal 16 layer and quarter λphase difference plates 140, 180, and the light is straightly polarizedin the lateral direction as shown in FIG. 10 to reach the TFT array sidepolarization reflector 58.

[0108] When voltage is applied, the quantity of birefringence of theliquid crystal layer 16 approaches 0, and the direction of polarizationis rotated by 90 degrees by the quantity of birefringence of the liquidcrystal 16 layer and quarter λ phase difference plates 140, 180, and thestraightly polarized light reaches the TFT array side polarizationreflector 58.

[0109] Herein, in the TFT array side polarization reflector 58, thelight straightly polarized in the specified direction, that is, in thelongitudinal direction is reflected to be a reflected light, and asindicated by arrow Lr in FIG. 7 and FIG. 8, it passes again through theTFT array side quarter λ phase difference plate 180, total transmissiontype liquid crystal display panel 101 b, CF side quarter λ phasedifference plate 140, CF side polarizer 13, front light 6, transparentcover 5 or the like, and is visually recognized by the user at the frontlight 6 side of the double-side display type liquid crystal displaydevice 10 (reflection type display).

[0110] Further, in the TFT array side polarization reflector 58, thelight straightly polarized to a direction perpendicular to the specifieddirection, that is, to the lateral direction passes therethrough, and asindicated by arrow Ld in FIG. 9 and FIG. 10, it passes again through theTFT array side polarizer 19, second quarter λ phase difference plate 40or the like, and is visually recognized by the user at the secondpolarizer (TFT array side polarizer 19) of the double-side display typeliquid crystal display device 10 (transmission type display).

[0111] At this time, as shown in FIG. 8 and FIG. 10, by the quantity ofbirefringence of the liquid crystal 16 layer determined by the voltageapplied to the TFT array side transparent electrode 23, and the quantityof birefringence of the quarter λ phase difference plates 140, 180, thereflectivity of the reflected light (arrow Lr) reflected by the TFTarray side reflection polarizer 58 varies from 0 to 1, and at the sametime, the transmissivity of the transmission light (arrow Ld) variesfrom 1 to 0. In result, the image can be displayed by setting thevoltage applied to the TFT array side transparent electrode 23 in everypixel 24 depending on the image.

[0112] Usually, as shown in FIG. 9, what is important is the contrast ofblack and white reversal by the liquid crystal 16 of the transmissionlight (arrow Ld) seen from the inside surface in the open state of thesecond main body 3 of the foldable mobile phone, and therefore it is setto heighten the transmissivity of the transmission light (arrow Ld) inthe state of low electric field determined by the TFT array sidetransparent electrode 23, and lower the transmissivity to approach 0when the electric field becomes higher and the TN liquid crystalmolecules are aligned perpendicularly to the glass substrates 15 and 17.

[0113] First, referring to FIG. 7, the display from the first polarizingmeans 13 is explained. By the quantity of birefringence of the liquidcrystal 16 layer determined by the voltage applied to the TFT array sidetransparent electrode 23, when setting the reflectivity of the reflectedlight (arrow Lr) reflected by the TFT array side reflection polarizer 58at 1, white color is displayed to the user from the first polarizer 13side (front light 6 side) shown in FIG. 7. Thus, unlike Embodiment 1,since there is no light missing loss through the transmission window 22,a higher reflection efficiency is obtained as compared with the case ofusing the reflection electrode 21 having a partial transmission portion(transmission window 22) as semitransmission reflecting means.

[0114] At this time, a further bright reflection image is realized whenthe reflectivity is higher when the reflectivity of the reflected light(arrow Lr) reflected by the TFT array side reflection polarizer 58 isset at 1. However, even if there is a slight absorption, it is noproblem in practical use. For example, when the reflectivity is set at1, if the light enters the TFT array side reflection polarizer 58 fromthe liquid crystal 16 layer, assuming the absorption rate to be 10% andreflectivity to be 90%, the brightness is lowered only by 10%, and it isno problem.

[0115] By the quantity of birefringence of the liquid crystal 16 layerdetermined by the voltage applied to the TFT array side transparentelectrode 23, when setting the reflectivity of the reflected light Lrreflected by the TFT array side reflection polarizer 58 at 0, thetransmissivity becomes 1, and the front light radiated light (arrow Li)passes through the TFT array side reflection polarizer 58 to betransmission light (arrow Ld). This transmission light (arrow Ld) passesthrough the TFT array side polarizer 19, and further passes the secondquarter λ phase difference plate 40, thereby illuminating the surface ofthe main body 1. This transmission light (arrow Ld) is reflected by thesurface of the first main body 1, and becomes a scattered reflectedlight (arrow Ls). When this scattered reflected light (arrow Ls) passesagain through the double-side display type liquid crystal display device10, and leaks in the direction of the transparent cover 5 at the frontlight 6 side to be visually recognized, it induces color oozing,contrast decline or contour blurring. In this Embodiment, however, thequarter λ phase difference plate 40 is provided at the outside of theTFT array side polarizer 19, and the scattered reflected light (arrowLs), after leaving the TFT array side polarizer 19, passes through thequarter λ phase difference plate 40 twice, and hence it becomes astraight polarized light orthogonal to the axis of polarization of theTFT array side polarizer 19, and is hence absorbed by the TFT array sidepolarizer 19 without passing therethrough. In result, a tight blackcolor is displayed to the user from the first polarizing means 13 side(front light 6 side) shown in FIG. 7.

[0116] This operation is exactly the same when external light (arrow Lo)enters by passing through the front light 6, and hence in an environmentof relatively less bright light, the external light and front light canbe used at the same time to visually recognize a bright and clearreflected image.

[0117] Next, referring to FIG. 9, the display from the second polarizingmeans 19 side when the second main body 3 is opened is explained. By thequantity of birefringence of the liquid crystal 16 layer determined bythe voltage applied to the TFT array side transparent electrode 23, whensetting the transmissivity of the transmission light (arrow Ld) passingthrough the TFT array side reflection polarizer 58 at 1, white color isdisplayed, and when setting at 0, black color is displayed. Thisoperation is exactly the same both in the case where the light radiatedby lighting the front light 6 enters and in the case where the externallight (arrow Lo) enters after passing through the front light 6, andtherefore in an environment of relatively less bright light, theexternal light and front light can be used at the same time to visuallyrecognize a bright and clear reflected image.

[0118] At this time, the external light (arrow Lo) illuminating thedouble-side display type liquid crystal display device from the userside (the second polarizing means 19 side) is a factor of lowering thecontrast of the display image, but since the TFT array side polarizer 19absorbs the straight polarized light in the direction of reflection ofthe TFT array side reflection polarizer 58, there is not happened thecase where the external light (arrow Lo) entering the double-sidedisplay type liquid crystal display device from the second polarizingmeans 19 side is reflected by the TFT array side reflection polarizer 58and hence reaches up to the eyes of the user at the second polarizingmeans 19 side.

[0119] Of the external light Lo, the light passing through the secondpolarizer 19 and reflection polarizer 58 and passing through the liquidcrystal cell is mostly absorbed or transmitted by the first polarizer 13regardless of the driving state of the liquid crystal 16, and is notreflected. Therefore, in a bright environment with external light Lo,the contrast of the transmission image is high.

[0120] Of the external light (arrow Lo) illuminating the double-sidedisplay type liquid crystal display device from the user side (thesecond polarizing means 19 side), the light passing through the TFTarray side polarizer 19 and TFT array side reflection polarizer 58 isreflected by the metal wiring 204 or TFT formed in the TFT array sideglass substrate 17, and is a factor to lower the contrast. But in thisEmbodiment, since a first quarter λ phase difference plate (TFT arrayside quarter λ phase difference plate 180) is provided between the TFTarray side glass substrate 17 and TFT array side reflection polarizer58, the light passes through the first quarter λ phase difference platein two reciprocal strokes so that the direction of polarization isrotated by 90 degrees, thereby the reflected light from the metal wiring204 and TFT cannot pass through the reflection polarizer 58 again.Therefore, the reflected light from the metal wiring 204 or TFT does notreach up to the eyes of the user at the second polarizing means 19 side,thereby preventing lowering of contrast by reflected light from themetal wiring 204 or TFT.

[0121] In this Embodiment, a third quarter λ phase difference plate 140is disposed between the liquid crystal 16 and first polarizing means 13,and same as in the case of the first quarter λ phase difference plate180, for the user from the front light 6 side, interlayer reflection orreflected light from the wiring member in the pixel boundary can be cutoff, and lowering of contrast by reflected light can be prevented.

[0122] In the foregoing Embodiment 1, similarly, of the external lightilluminating the double-side display type liquid crystal display devicefrom the second polarizing means 19 side, if the light passing throughthe TFT array side polarizer 19 is reflected by the metal wiring 204,TFT, reflection electrode 21 formed on the TFT array side glasssubstrate 17, it is a cause of lowering the contrast when observing fromthe second polarizing means 19 side. But, the Embodiment includes theTFT array side phase difference plate 18 disposed between the TFT arrayside glass substrate 17 and second polarizing means, and by setting thequantity of birefringence of this phase difference plate 18 at aboutquarter λ, the direction of polarization is rotated since the lightpasses through the phase difference plate 18. Thus, the reflected lightfrom the metal wiring 204, TFT and reflection electrode 21 cannot passthrough the TFT array side polarizer 19 again. Therefore, the reflectedlight from the metal wiring 204, TFT and reflection electrode 21 doesnot reach up to the eyes of the user at the second polarizing means 19side, thereby preventing lowering of contrast by reflected light fromthe metal wiring 204, TFT and reflection electrode 21.

[0123] As explained also in the foregoing Embodiment 1, the relationbetween the applied voltage of the liquid crystal 16 layer andbrightness is inverted between when the foldable mobile phone is seenfrom the inside of the folded state and when seen from the outside, andtherefore the gradation of the display image data must be invertedbeforehand depending on whether in opened state or in closed state. Atthe same time, the data conversion is necessary to invert the image dataupside down in the case of vertical folding or invert the image dataright and left in the case of lateral folding. Specifically, in FIG. 6relating to Embodiment 2, the data converting means 64 incorporates afunction of shuffling image data and converting the gradation at thesame time, and by detecting the opening or closing of the informationappliance, the image data is shuffled and the gradation is convertedautomatically. Moreover, by disposing an external changeover switch, theuser can change over.

[0124] In the foregoing description, the first electrode is the CF sidetransparent electrode 26 and the second electrode is the TFT array sidetransparent electrode 23, but same effects are obtained, to thecontrary, when the first electrode is the TFT array side transparentelectrode 23 and the second electrode is the CF side transparentelectrode 26.

[0125] Similarly, in the foregoing description, the first electrode andfirst polarizer at the front light side of the liquid crystal 16 layerare at the color filter side, and the second electrode and secondpolarizer are at the TFT array side, but same effects are obtained, tothe contrary, when the first electrode and first polarizer are at theTFT array side, and the second electrode and second polarizer are at thecolor filter (CF) side.

Embodiment 4

[0126]FIG. 11 and FIG. 12 are diagrams explaining a double-side displaytype liquid crystal display device and an information appliance usingthe same according to Embodiment 4 of the present invention, and morespecifically FIG. 11 is a sectional view of essential parts of thedouble-side display type liquid crystal display device, and FIG. 12(a),(b) are partially magnified sectional views of the double-side displaytype liquid crystal display device in FIG. 11 and in a comparativeexample. FIG. 12(a), (b) are drawn in a dimensional ratio close to theactual aspect ratio of width and thickness.

[0127] In FIG. 11 and FIG. 12, reference numeral 78 denotes a CF sidereflection polarizer disposed between the liquid crystal 16 and secondpolarizing means (CF side polarizer 13), for reflecting the straightlight polarized in a specified direction, and transmitting the straightlight polarized in a direction perpendicular thereto.

[0128] In the foregoing Embodiment 3, the first polarizing means is theCF side polarizer 13, the second polarizing means is the TFT array sidepolarizer 19, the first electrode is the CF side transparent electrode26, the second electrode is the TFT array side transparent electrode 23,the first substrate is the CF side glass substrate 15, the secondsubstrate is the TFT array side glass substrate 17, and the TFT arrayside reflection polarizer 58 is disposed between the second substrate(TFT array side glass substrate 17) and second polarizing means (TFTarray side polarizer 19), whereas in this Embodiment, the firstpolarizing means is the TFT array side polarizer 19, the secondpolarizing means is the CF side polarizer 13, the first electrode is theTFT array side transparent electrode 23, the second electrode is the CFside transparent electrode 26, the first substrate is the TFT array sideglass substrate 17, the second substrate is the CF array side glasssubstrate 15, and the CF side reflection polarizer 78 is disposedbetween the second substrate (CF glass substrate 17) and secondelectrode (the CF side transparent electrode 26).

[0129] The other configuration of the double-side display type liquidcrystal display device of the Embodiment and the information applianceusing the same is same as in Embodiment 3.

[0130] Mainly different points from Embodiment 3 are explained below.The double-side display type liquid crystal display device according tothe Embodiment comprises a front light 6 composed of a light source 11and a front light light-conducting plate 12, a TFT array side glasssubstrate 17, a CF side glass substrate 15, and a liquid crystal 16layer of, for example, TN liquid crystal held between these twosubstrates 17 and 15. A TFT array side transparent electrode 23 (firstelectrode) to which a voltage is applied through a gate TFT 20 isprovided at the inner side (liquid crystal 16 layer side) of the TFTarray side glass substrate 17 (first substrate), and a first quarter λphase difference plate (TFT array side quarter λ phase difference plate180) and a TFT array side polarizer 19 as first polarizing means aresequentially adhered to the outer side (the opposite side of the liquidcrystal 16 layer) of the TFT array side glass substrate 17. At the innerside of the CF side glass substrate 15 (second substrate), a reflectionpolarizer 78 and a third quarter λ phase difference plate (CF sidequarter λ phase difference plate 140) are sequentially adhered, andfurther a CF 25 and a CF side transparent electrode 26 (secondelectrode) are formed, and at the outer side of the CF side glasssubstrate 15, a CF side polarizer 13 is adhered, and at the furtherouter side, a quarter λ phase difference plate 40 is adhered.

[0131] The detail of operation of the double-side display type liquidcrystal display device of the Embodiment is explained below by referringto a case of lighting of the front light 6.

[0132] The light (arrow L) emitted from the light source 11 spreads bydiffusing and propagating through the light-conducting plate 12, and isradiated by a reflection prism 12 a provided in the light-conductingplate 12 to the TFT array side polarizer 19 side. The radiated light(arrow Li) is straightly polarized by the TFT array side polarizer 19,and passes through the TFT array side quarter X phase difference plate180, TFT array side glass substrate 17, TFT array side transparentelectrode 23, liquid crystal 16 layer, CF side transparent electrode 26,CF 25, and CF side quarter λ phase difference plate 140, to reach the CFside polarizer 78.

[0133] In the CF side reflection polarizer 78, the light straightlypolarized in a certain direction (a specified direction) is reflected tobe a reflected light (arrow Lr), and the light straightly polarized in aperpendicular direction is transmitted to be a transmission light (arrowLd).

[0134] At this time, by the quantity of birefringence of the liquidcrystal 16 layer determined by the voltage applied to the TFT array sidetransparent electrode 23, the reflectivity of the reflected light (arrowLr) reflected by the CF side reflection polarizer 78 varies from 0 to 1,and at the same time, the transmissivity of the transmission light(arrow Ld) varies from 1 to 0. In result, the image can be displayed bysetting the voltage applied to the TFT array side transparent electrode23 in every pixel depending on the image.

[0135] Next, referring to FIGS. 12(a) and (b), there is explainedeffects obtained when the reflection polarizer 78 is disposed betweenthe second substrate (CF side glass substrate 17) and the secondelectrode (CF side transparent electrode 26).

[0136] As shown in FIG. 12(b), when the color filter (CF) sidereflection polarizer 78 is adhered to the outer side of the CF sideglass substrate 15, as compared with the width of 50 to 100 μm at thenarrower side of one pixel of an ordinarily rectangular CF 25, thethickness of the CF side glass substrate 15 is as much as 300 to 700 μm,and therefore the distance from the CF side reflection polarizer 78 tothe CF 25 (the thickness totaling the CF side glass substrate 15, CFside quarter λ phase difference plate 140, and half of CF sidereflection polarizer 78) is 500 to 900 μm, which is about 10 timeslonger than the width of the pixel of the CF 25, and hence a depth angleθ_(B) of the width of one pixel of the CF 25 from the CF side reflectionpolarizer 78 is small, about 3 degrees.

[0137] Therefore, the majority of the light reflected by the reflectionpolarizer 78 passes through a CF pixel of a different color adjacent tothe CF pixel passing at the time of incidence, and since thetransmission wavelength is different, re-absorption is sufficient, andabout ⅔ of the light is re-absorbed in average. Therefore, brightreflected image is not obtained.

[0138] As known from a simple geometric calculation, when the lightenters the CF side glass substrate 15 of refractive index of 1.5 fromthe direction of 30 degrees of the largest quantity of external lightincidence, preferably, by setting the glass thickness within two timesof the width of the narrower side of the CF 25, the possibility of thereflected light passing the same CF pixel as at the time of incidence ishigher, and re-absorption is smaller, so that the reflectivity ishigher.

[0139] When using the light of the front light 6, the divergence angleis about 15 degrees, and in this case where the thickness of the glassis set in a dimension of within 5 times of the width of the narrowerside of the CF 25, the possibility of the reflected light passing thesame CF pixel as at the time of incidence is higher, and re-absorptionis smaller, so that the reflectivity is higher. Therefore, in thedouble-side display type liquid crystal display device 10 of thefoldable mobile phone according to Embodiment 3, by defining thethickness of the second glass substrate for adhering thereto thereflection polarizer 58 within 5 times, preferably 2 times of the widthof the narrower side of the color filter pixel, a reflected image ofhigh reflectivity can be visually recognized from the front light 6side.

[0140] By contrast, as shown in FIG. 12(a), in this Embodiment havingthe CF side reflection polarizer 78 adhered to the inner side of the CFside glass substrate 15, the distance from the CF side reflectionpolarizer 78 to the CF 25 (the thickness totaling the CF side quarter λphase difference plate 140, and half of CF side reflection polarizer 78)is short, about 50 to 100 μm, and hence the depth angle OA is large,about 25 to 90 degrees. In result, the possibility of the reflectedlight (arrow Lr) passing the pixel of the same CF 25 as the incidentlight (arrow Li) is higher. Therefore, the possibility of the incidentlight (arrow Li) and reflected light (arrow Lr) passing the pixels ofthe color filter 25 of different colors is lowered, and re-absorption ofthe reflected light (arrow Lr) by the CF 25 at the time of passing theCF 25 is suppressed, and the reflectivity is much enhanced.

[0141] Thus, when the CF 25 is disposed at the second electrode sideinstead of the first electrode side, and the reflection polarizer 78 isdisposed between the second substrate (CF side glass substrate 17) andsecond electrode (CF side transparent electrode 26), the reflectivity islargely enhanced in reflection type display, so that a bright display isrealized.

[0142] Further, in the reflection type display, since second substrate17 is not present between the reflecting means 78 and first polarizingmeans 19, as compared with the case of disposing the second substrate 17shown in FIG. 12(b), the optical path is shortened, and hence theparallax in display image is decreased.

[0143] As explained so far, the reflection polarizer 78 is adhered tothe color filter 25, but the present invention is not limited to this,and the same effects are obtained when adhered to the TFT array sidesubstrate 17.

[0144] However, since the reflection polarizer 78 is made of resin, itcannot withstand high temperature process, and it is better to adhere tothe color filter 25 which is relatively lower in process temperature, inwhich degeneration of the reflection polarizer 78 (deterioration ofreflection polarizing characteristic) in the high temperature process issmaller, and hence the reflectivity is enhanced largely.

Embodiment 5

[0145]FIG. 13 and FIG. 14 are diagrams explaining a double-side displaytype liquid crystal display device and an information appliance usingthe same according to Embodiment 5 of the present invention, and morespecifically, FIG. 13 is a sectional view of essential parts of thedouble-side display type liquid crystal display device, and FIG. 14(a)to (c) are sectional views explaining a manufacturing method of thedouble-side display type liquid crystal display device in FIG. 13.

[0146] The double-side display type liquid crystal display device andthe information appliance using the same of the Embodiment are similarto Embodiment 4, except that the second substrate (CF side glasssubstrate 15) is omitted.

[0147] In this Embodiment, since the second substrate (CF side glasssubstrate 15) is omitted, there is no glass substrate between the CFside reflection polarizer 78 and the CF 25. Therefore, same as explainedin Embodiment 4 using FIG. 12(a), the depth angle θ_(C) of width of onepixel of the CF 25 from the CF side reflection polarizer 78 is large,about 25 to 90 degrees, and the reflectivity in reflection type displayis largely enhanced.

[0148] Further, in reflection type display, since there is no secondsubstrate between the reflecting means 78 and first polarizing means 19,as compared with the case where the second substrate 17 exists as shownin FIG. 12(b), the optical path is shorter, and hence the parallax inthe display image is reduced.

[0149] Further, in this Embodiment, since the second substrate (CF sideglass substrate 15) is omitted, the weight is reduced at the same time.

[0150] Referring now to FIG. 14, the manufacturing method of thedouble-side display type liquid crystal display device of the Embodimentis explained.

[0151] First, the TFT array side glass substrate 17 (first substrate)and CF side glass substrate 15 (second substrate) are adhered togetherwith a gap being provided therebetween to form a cell, and the gap isfilled with liquid crystal 16 to form a liquid crystal cell, and then aTFT array side quarter λ phase difference plate 180 (first quarter λphase difference plate) and a TFT array side polarizer 19 (firstpolarizer) are adhered to the TFT array side glass substrate 17 (FIG.14(a)).

[0152] Electrode terminals and other metal parts formed on the two glasssubstrates 15 and 17 are sufficiently protected with inorganic materialor organic material, and the entire structure is etched by hydrofluoricacid, and the CF side glass substrate 15 is removed (FIG. 14(b)).

[0153] A quarter λ phase difference plate 40 (second quarter λ phasedifference plate), a reflection polarizer 78, a CF side polarizer 13(second polarizer), a CF side quarter λ phase difference plate 140(third quarter λ phase difference plate) are adhered to the CF 25 (FIG.14(c)).

[0154] As explained so far, the first substrate is the TFT array sideglass substrate 17, the second substrate is the CF side glass substrate15, the CF side glass substrate 15 is removed, and the reflectionpolarizer 78 is adhered to the CF 25, but same effects are obtained, tothe contrary, if the first substrate is the CF side glass substrate 15,the second substrate is the TFT array side glass substrate 17, the TFTarray side glass substrate 17 is removed, and the reflection polarizer78 is directly adhered to the TFT array.

Embodiment 6

[0155]FIG. 15 is a diagram explaining a double-side display type liquidcrystal display device and an information appliance using the sameaccording to Embodiment 6 of the present invention, and morespecifically it is a sectional view of essential parts of thedouble-side display type liquid crystal display device.

[0156] In FIG. 15, reference numerals 31 and 32 denote first and secondpolarizing means, respectively, disposed oppositely on both sides of aliquid crystal, and same polarizers as in the foregoing Embodiments areused. Reference numerals 33 and 34 denote first and second substrates,respectively, disposed between the liquid crystal 16 layer and the firstand second polarizing means 31 and 32, respectively, and same glasssubstrates as in the foregoing Embodiments are used.

[0157] Reference numerals 35 and 36 denote first and second electrodesfor driving the liquid crystal 16 and controlling its quantity ofbirefringence. In the foregoing Embodiments, the first and secondelectrodes are disposed between the liquid crystal 16 layer and thefirst and second polarizing means, respectively, and the liquid crystal16 layer is held between the first and second electrodes, but in thisEmbodiment, the first and second electrodes 35 and 36 are both disposedbetween the second polarizing means 32 and liquid crystal 16. Morespecifically, the first electrode 35 and second electrode 36 are bothdisposed on the surface of the second substrate 34 as mutually engagedtooth-shaped electrodes, and the liquid crystal 16 is driven by anelectric field formed by the first electrode 35 and second electrode 36and having components parallel to the surface of the second substrate34.

[0158] Reference numerals 37 and 38 denote second and third quarter λphase difference plates, and same plates as in the foregoing Embodimentsare used. Reference numeral 39 denotes a reflection polarizer forreflecting the light polarized straightly in a specified direction, andtransmitting the light straightly polarized in a direction perpendicularto the specified direction, and the same one as in the foregoingEmbodiments is used.

[0159] Reference numeral 101 c denotes a liquid crystal display panelhaving a liquid crystal 16, and first and second electrodes 35 and 36for driving the liquid crystal 16, and in this Embodiment, this is atotal transmission type liquid crystal display panel for transmittingall light passing through the liquid crystal 16. Such total transmissiontype liquid crystal display panel 101 c is disclosed in, for example,Japanese Examined Patent Publication No. 21907/1998, and it is usuallycalled a liquid crystal panel of IPS (in-plane switching: lateralelectric field application) system. In contrast to this, the totaltransmission type liquid crystal display panel 101 b shown in Embodiment3 is called a liquid crystal display panel of longitudinal electricfield application system.

[0160] The double-side display type liquid crystal display device andinformation appliance using the same according to this Embodiment aresame as the double-side display type liquid crystal display device andinformation appliance using the same according to Embodiment 3, exceptthat the total transmission type liquid crystal display panel 101 c oflateral electric field application system is used instead of the totaltransmission type liquid crystal display panel 101 b of longitudinalelectric field application system, and mainly the location and structureof the first and second electrodes and direction of electric field fordriving the liquid crystal 16 are different, and other structure andoperation are same as in Embodiment 3.

[0161] Although description of the operation is omitted, in thisEmbodiment, too, same as in Embodiment 3, the light straightly polarizedin a specified direction, that is, a part of the light passing from thefront light side to the liquid crystal 16 and reaching the reflectionpolarizer 39 is reflected by the reflection polarizer 39, and reachesthe first polarizing means 31, and the remainder, that is, the lightstraightly polarized in a direction perpendicular to the specifieddirection passes through the reflection polarizer 39, and reaches thesecond polarizing means 32. In result, the display image can be visuallyrecognized from both sides of the first polarizing means 31 side andsecond polarizing means 32 side.

[0162] Further, though the external light illuminating the liquidcrystal display device from the second polarizing means 32 side is afactor of lowering the contrast of the transmission type display image,since the second polarizing means 32 absorbs the straight polarizedlight in the direction of reflection of the reflection polarizer 39, itis effective to heighten the contrast.

[0163] Effects of first, second and third quarter λ phase differenceplates 40, 37 and 38 are same as in Embodiment 3.

[0164] As explained herein, both of the first electrode 35 and secondelectrode 36 are disposed between the second polarizing means 32 andliquid crystal 16, but the first electrode 35 and second electrode 36might be also disposed between the first polarizing means 31 and liquidcrystal 16, and same effects are obtained.

[0165] As semitransmission reflecting means, the reflection polarizer 39is disposed between the first quarter λ phase difference plate 37 andsecond polarizing means 32, but instead of the reflection polarizer 39,by using a reflector having transmission window (for example, analuminum vapor deposition mirror film having multiple fine transmissionwindows) same as explained in Embodiment 1, the reflector havingtransmission window might be adhered, for example, to the liquid crystal16 side of the second substrate 34.

[0166] So far, there is shown a case where, in the double-side displaytype liquid crystal display device and information appliance using thesame according to Embodiment 3, the total transmission type liquidcrystal display panel 101 c of lateral electric field application systemis used instead of the total transmission type liquid crystal displaypanel 101 b of longitudinal electric field application system. Thepresent invention is not, however, limited to this, and in thedouble-side display type liquid crystal display device and informationappliance using the same according to Embodiment 4 or 5, similarly, thetotal transmission type liquid crystal display panel 101 c of lateralelectric field application system might be used instead of the totaltransmission type liquid crystal display panel 101 b of longitudinalelectric field application system.

Embodiment 7

[0167]FIG. 16 to FIG. 18 are diagrams explaining a double-side displaytype liquid crystal display device and an information appliance usingthe same according to Embodiment 7 of the invention, and morespecifically FIG. 16 is a magnified sectional view of essential parts ofa foldable mobile phone as an information appliance, and FIG. 17 andFIG. 18 are explanatory diagrams showing examples of the direction ofpolarization of each light shown in FIG. 16.

[0168] In FIG. 16, reference numeral 204 a denotes a conductive layermade of metal such as chromium or aluminum disposed at the liquidcrystal 16 side, and 204 b a low reflection layer made of, for example,chromium oxide lower in reflectivity of light than the conductive layer204 a, being disposed at the opposite side (second substrate 17 side) ofthe liquid crystal 16. In this Embodiment, the metal wiring 204 disposedin the second substrate (TFT array side glass substrate 17) forsupplying voltage to the second electrode (TFT array side transparentelectrode 23) has a two-layer structure of conductive layer 204 a andlow reflection layer 204 b.

[0169] Usually, the metal wiring 204 of, for example, source wiring orgate wiring is formed by etching and patterning the film of chromium oraluminum formed on the glass substrate by sputtering or the like, andtherefore the surface of the glass substrate side is a mirror-smoothsurface of high reflectivity. Therefore, as explained in Embodiment 3,the light passing through the TFT array side polarizer 19 and TFT arrayside reflection polarizer 58, out of the external light (arrow Lo)illuminating the double-side display type liquid crystal display devicefrom the second polarizing means 19 side, is reflected by the metalwiring 204 formed on the TFT array side glass substrate 17, which is acause to lower the contrast.

[0170] To prevent this, in Embodiment 3, the first quarter λ phasedifference plate (TFT array side quarter λ phase difference plate 180)is provided to prevent the reflected light at the metal wiring 241 frompassing again through the reflection polarizer 58.

[0171] In this Embodiment, in contrast thereto, the low reflection layer204 b of lower reflection of light than that of the conductive layer 204a is formed on the TFT array side glass substrate 17, and the conductivelayer 204 a is formed thereon to realize the metal wiring 204 oftwo-layer structure.

[0172] Since the metal wiring 204 has a two-layer structure, the lightpassing through the TFT array side polarizer 19 and TFT array sidereflection polarizer 58 and reaching the metal wiring 204, out of theexternal light (arrow Lo) illuminating the double-side display typeliquid crystal display device from the second polarizing means 19 side,reaches the low reflection layer 204 b, and reflection is suppressed,thereby preventing decline of contrast by the reflected light by themetal wiring 204.

[0173] With the use of FIG. 16 to FIG. 18, the operation of thedouble-side display type liquid crystal display device of the Embodimentis explained below, mainly by referring to the different points fromEmbodiment 3.

[0174] The light emitted from the light source 11 (arrow L) spreads bydiffusing and propagating through the light-conducting plate 12, and isradiated by the reflection prism 12 a provided in the light-conductingplate 12 to the CF side polarizer 13 side. The radiated light (arrow Li)is straightly polarized by the CF side polarizer 13 (in FIG. 17 and FIG.18, a straightly polarized light in the lateral direction), and reachesthe total transmission type liquid crystal display panel 101 d.

[0175] In the total transmission type liquid crystal display panel 101d, when voltage is applied between the CF side transmission electrode 26and TFT array side transparent electrode 23, the direction ofpolarization is not rotated as shown in FIG. 17, and the light isdirectly transmitted in the lateral direction and is reflected by thereflection polarizer 58. The reflected light (arrow Lr) passes againthrough the total transmission type liquid crystal display panel 101 d,CF side polarizer 13, front light 6, and transparent cover 5, and isvisually recognized by the user at the front light 6 side of thedouble-side display type liquid crystal display device 10 (reflectiontype display).

[0176] In the total transmission type liquid crystal display panel 101d, when voltage is not applied between the CF side transmissionelectrode 26 and TFT array side transparent electrode 23, the directionof polarization is rotated by 90 degrees by the liquid crystal layer asshown in FIG. 18, and the light is straightly polarized in thelongitudinal direction and is issued, and passes through the reflectionpolarizer 58, TFT array side polarizer 19 and second quarter λ phasedifference plate 40, and is visually recognized by the user at thesecond polarizer (TFT array side polarizer 19) side of the double-sidedisplay type liquid crystal display device 10 (transmission typedisplay).

[0177] As explained so far, in Embodiment 3, the metal wiring (sourcewiring) 204 for supplying a voltage to the TFT array side transparentelectrode 23 is a two-layer structure consisting of the conductive layer204 a disposed at the liquid crystal 16 side, and a low reflection layer204 b of lower reflectivity of light than that of the conductive layer204 a disposed at the opposite side (TFT array glass substrate 17 side)of the liquid crystal 16, but in other Embodiments, other metal wiring(gate wiring) for supplying a voltage to the first electrode or secondelectrode might be also composed of a metal wiring of two-layerstructure, in which similar effects are obtained.

[0178] Preferably, the metal wiring formed at the position closest tothe TFT array glass substrate 17 is formed in a two-layer structure ofthe conductive layer 204 a and the low reflection layer 204 b of lowerreflectivity of light than that of the conductive layer 204 a same asmentioned above. By etching and patterning, simultaneously when formingthe wiring, the film for two-layer structure metal wiring in a shape forshielding optically, in order to suppress the reflection of electricelements of higher reflectivity such as other metal wiring or transistorformed nearer to the liquid crystal 16 than the metal wiring layer, ifthere is reflection of other member such as transistor, a low reflectionlayer is formed similarly at the opposite side of the liquid crystal 16layer of the member, so that lowering of contrast can be prevented. Atthis time, an insulating layer might be interposed between other membersuch as transistor and the low reflection layer.

[0179] The low reflection layer 204 b is preferred to be black, but thecolor is not specifically limited.

[0180] The low reflection layer 204 b is not required to be a completelyblack two-layer structure, but similar effects are expected as far as itis disposed optically closely in a shape conforming to the shape of theconductive layer 204 a. In the two-layer structure, however, since theprocess is finished by one step of transfer, the cost is lower.

[0181] The technical scope of the present invention is not limited tothe foregoing Embodiments 1 to 7, but might be changed and modified invarious manners without departing from the spirit and scope of thepresent invention.

[0182] For example, the liquid crystal display device is not limited tothe illustrated example of TFT system, but includes, for example, asimple matrix system LCD (liquid crystal display device). The writingmanner of the TFT liquid crystal panel is not limited to the so-calledline sequential system, but same effects are obtained, for example, bythe dot sequential system by varying vertical direction of writing.

[0183] In the foregoing Embodiments, the surface of the front light 6side of the double-side display type liquid crystal display 10 isdisposed at the outer side of the second main body 3, and the surface ofthe second polarizing means 19 side of the double-side display typeliquid crystal display 10 is disposed at the inner side. But thedirection of location of the double-side display type liquid crystaldisplay 10 might be inverted, and in such a case, when the second mainbody 3 is opened, the reflection type display with front light 6 isrealized, and the display image can be visually recognized byillumination of external light or front light 6. Therefore, in the casewhere external light is sufficiently available, the display image can bevisually recognized without consuming the electric power by lighting thefront light 6. When the second main body 3 is closed, by using the frontlight 6 as the light source of the backlight, transmission type displayis realized, and the display image can be visually recognized bylighting of the front light 6.

[0184] From the viewpoint of saving the power consumption by lighting ofthe front light 6, the direction of location of the double-side displaytype liquid crystal display 10 might be determined depending on theduration of the time of opening state or closing state of the secondmain body 3.

[0185] The above explanation is made based on mobile phone as anexample, but the present invention is not limited to this, and similareffects are obtained in any other information appliance comprising afirst main body having various operation switches and a second main bodyhaving display means for visibly displaying various kinds ofinformation, such as foldable PDA, foldable wristwatch having a firstmain body fixed to the wrist, and foldable calculator.

[0186] For example, in a foldable PDA, when the second main body isclosed, the image to be displayed in the double-side display type liquidcrystal display includes, for example, the calendar, clock, schedule,illustration, portrait, game application, map, internet HP, decorativepattern, and decorative illumination, and when the second main body isopened, the image to be displayed in the double-side display type liquidcrystal display includes the document writing screen, mail operationscreen, setting screen or the like.

[0187] In a foldable wristwatch, when the second main body is closed,the image to be displayed in the double-side display type liquid crystaldisplay includes, for example, the calendar and the clock, and when thesecond main body is opened, the image to be displayed in the double-sidedisplay type liquid crystal display includes the alarm setting screen,schedule setting screen or the like.

[0188] In the Embodiments explained so far, the double-side display typeliquid crystal display of the invention is used as the display device ofthe information appliance, and the information appliance is designed torecognize the display image visually by the same liquid display deviceboth in the cases where the second main body having the display deviceis opened and where the same is closed, but the present invention is notlimited to this, and it might be also used as the display device servingalso as a cover for concealing the setting switch in an appliance havinga setting switch not used in ordinary operation, such as refrigerator,microwave oven, room cooler and other electric household appliance.Moreover, in the double-side display type liquid crystal display of theinvention, since the display image can be recognized simultaneously fromboth sides of the first polarizing means side and second polarizingmeans side, it can be also used as a display device for face-to-facegame application played by two players sitting opposite to each other.

[0189] Thus, according to the double-side display type liquid crystaldisplay of the present invention comprising a liquid crystal, first andsecond electrodes for driving the liquid crystal, first and secondpolarizing means disposed on both sides of the liquid crystal, a frontlight disposed at the opposite side of the liquid crystal of the firstpolarizing means, and semitransmission reflecting means disposed at thesecond polarizing means side of the liquid crystal for passing a part oflight from the front light side passing through the liquid crystal, inwhich the first polarizing means is optically disposed so as to absorbor transmit the light passing through the liquid crystal, and the secondpolarizing means is optically disposed so as to absorb or transmit thelight passing through the liquid crystal and then passing through thesemitransmission reflecting means. Therefore, the light, both frontlight and external light, reaching the semitransmission reflecting meansby passing through the first polarizing means and liquid crystal fromthe front light side partly passes through the semitransmissionreflecting means and reaches the second polarizing means, and the lightdimmed according to the driving state of the liquid crystal passesthrough the second polarizing means to be radiated to outside of thedouble-side display type liquid crystal display device (transmissiontype display). At this time, if the surrounding is bright, the externallight entering the liquid crystal from the second polarizing means isnot reflected, so that transmission type display of high contrast isrealized. A part of the light is reflected by the semitransmission typereflecting means and passes again the liquid crystal to reach the firstpolarizing means, and the light dimmed according to the driving state ofthe liquid crystal passes through the first polarizing means, andfurther passes through the front light to be radiated to outside of thedouble-side display type liquid crystal display device (reflection typedisplay). In result, a bright display screen of excellent displayquality can be recognized from both sides of the first polarizing meansside and second polarizing means side.

[0190] Further, the semitransmission reflecting means is a reflectordisposed between the liquid crystal and the second polarizing means, andhaving a transmission window for passing a part of the light from thefront light side passing through the liquid crystal, so that the lightreaching the reflector after passing through the first polarizing meansand liquid crystal from the front light side partly passes through thetransmission window of the reflector to reach the second polarizingmeans, while the remainder is reflected by the reflector to reach thefirst polarizing means. In result, the display image can be visuallyrecognized from both sides of the first polarizing means side and secondpolarizing means side.

[0191] The first and second electrodes are transparent electrodesdisposed between the liquid crystal and first polarizing means and theliquid crystal and second polarizing means respectively, and thereflector having a transmission window is disposed at the opposite sideof the liquid crystal of the second electrode, so that the lightreaching the reflector having the transmission window after passingthrough the first polarizing means, first electrode, liquid crystal, andsecond electrode from the front light side partly passes through thetransmission window of the reflector to reach the second polarizingmeans, and the remainder is reflected by the reflector to reach thefirst polarizing means. In result, the display image can be visuallyrecognized from both sides of the first polarizing means side and secondpolarizing means side.

[0192] Moreover, the semitransmission reflecting means is a reflectionpolarizer disposed between the liquid crystal and the second polarizingmeans, for reflecting the light having a specified polarizingcharacteristic and passing all other light, so that the light having aspecified polarizing characteristic which is a part of the lightreaching the reflection polarizer after passing through the liquidcrystal from the front light side is reflected by the reflectionpolarizer to reach the first polarizing means, and the remaining lightmostly passes through the reflection polarizer to reach the secondpolarizing means, thereby the display image can be visually recognizedfrom both sides of the first polarizing means side and second polarizingmeans side. At this time, for the light of the specified polarizingcharacteristic, since the entire surface of the reflection polarizer isthe reflection plane, a high reflectivity is expected, while for theother light than the light of the specified polarizing characteristic,to the contrary, since the entire surface of the reflection polarizer isthe transmission plane, a high transmissivity is expected.

[0193] Further, the device includes first and second glass substratesholding the liquid crystal therebetween and disposed between the liquidcrystal and the first and second polarizing means respectively, and acolor filter provided at a liquid crystal side of either first or secondglass substrate, a reflection polarizer is adhered to the opposite sideof the liquid crystal of the second substrate, and the thickness of thesecond substrate is 5 times or less of the narrowest width of the colorfilter, so that re-absorption of reflected light by the color filter canbe suppressed, thereby a bright reflected image can be visuallyrecognized.

[0194] Further, the device includes a metal wiring electricallyconnected to the first electrode or second electrode, a first quarter λphase difference plate is disposed between the metal wiring and firstpolarizing means when the metal wiring is located between the liquidcrystal and the first polarizing means, or between the metal wiring andreflection polarizer when the metal wiring is located between the liquidcrystal and reflection polarizer, so that when the metal wiring islocated between the liquid crystal and first polarizing means, a part ofthe light passing through the first polarizing means is reflected by themetal wiring, but the direction of polarization is rotated by 90 degreessince the reflected light has already passed the quarter λ phasedifference plates by two reciprocal strokes, so that the light cannotpass the first polarizing means again. On the other hand, when the metalwiring is located between the liquid crystal and the reflectionpolarizer, a part of the external light passing through the secondpolarizing means and reflection polarizer is reflected by the metalwiring, but the direction of polarization is rotated by 90 degrees sincethe reflected light has already passed the quarter λ phase differenceplates by two reciprocal strokes, so that the light cannot pass thereflection polarizer again. Therefore, the reflected light by the metalwiring does not reach up to the eyes of the observer, and lowering ofcontrast by reflected light from the metal wiring can be prevented.

[0195] Further, the device includes a metal wiring electricallyconnected to the first electrode or second electrode, and a lowreflection layer of lower reflectivity of light than that of the metalwiring is disposed at the opposite side of the liquid crystal of themetal wiring, being disposed optically closely in a shape after themetal wiring, so that a part of the light passing through the polarizingmeans at the opposite side of the liquid crystal of the metal wiring isreflected by the surface of the metal wiring, but the reflection issuppressed by the low reflection layer, thereby a high contrast might beobtained.

[0196] An information appliance of the present invention is aninformation appliance comprising a first main body having variousoperation switches, and a second main body having display means forvisually displaying various kinds of information, being coupled to thefirst main body in an opening and closing manner, in which the displaymeans is a double-side display type liquid crystal display devicecomprising a liquid crystal, first and second electrodes for driving theliquid crystal, first and second polarizing means disposed on both sidesof the liquid crystal, a front light disposed at the opposite side ofthe liquid crystal of the first polarizing means, and semitransmissionreflecting means disposed at the second polarizing means side of theliquid crystal for passing a part of light from the front light sidepassing through the liquid crystal, and in which windows are disposed atthe inner side of the casing of the inside and at the outer side of theoutside when the second main body is closed, the surface of the frontlight side of the double-side display type liquid crystal display deviceis disposed at one window, and the surface of the second polarizingmeans side of the double-side display type liquid crystal display deviceis disposed at the other. Therefore, without requiring an extra imagedisplay device, the display image can be visually recognized by a sameliquid crystal display device both in the case where the second mainbody is opened and in the case where the same is closed.

[0197] The surface of the front light side of the double-side displaytype liquid crystal display device is disposed at the window provided atthe outer side of the second main body, and the surface of the secondpolarizing means side of the double-side display type liquid crystaldisplay device is disposed at the window provided at the inner side, sothat the reflection type display by the front light is possible when thesecond main body is closed, and the display image can be visuallyrecognized by external light or lighting of front light. Therefore, inthe case where external light is sufficiently available, the displayimage can be visually recognized without consuming electric power bylighting of the front light. Also in the case where the second main bodyis opened, transmission type display using front light as the lightsource of backlight is possible, and the display image can be visuallyrecognized by lighting the front light.

[0198] The appliance further includes opening/closing judging means forjudging the opening or closing of the second main body, and a frontlight lighting switch which cooperates with the opening/closing judgingmeans for lighting the front light when the main body is judged to beopened, so that when the second main body is opened, the front lightlights up automatically, and the display image can be visuallyrecognized.

[0199] The appliance further includes writing direction inverting meansfor inverting the writing direction of display image data into eachpixel of the double-side display type liquid crystal display device inthe vertical or lateral direction, so that when the second main bodyopens and closes in the vertical direction, the writing direction of thedisplay image data into each pixel of the double-side display typeliquid crystal display device is inverted in the vertical directiondepending on the opening or closing state of the second main body, whilein the case of opening and closing in the lateral direction, it isinverted in the lateral direction, thereby display image in the correctdirection can be visually recognized without changing the holdingposition when opening or closing the second main body.

[0200] The appliance further includes data converting means forconverting the data of display image into data inverted in the verticalor lateral direction, so that when the second main body opens and closesin the vertical direction, the display image data is shuffled upsidedown depending on the opening or closing state of the second main body,while in the case of opening and closing in the lateral direction, it isinverted by shuffling right and left, thereby the display image in thecorrect direction can be visually recognized without changing theholding position when opening or closing the second main body.

[0201] The appliance further includes data converting means forconverting the gradation of the data of display image, so that thedisplay is shown always in correct color both in the case where thesecond main body is opened and in the case where it is closed.

[0202] The appliance further includes a second quarter % phasedifference plate disposed at the opposite side of the liquid crystal ofthe second polarizing means of the double-side display type liquidcrystal display device, so that when viewing the display screen of thefirst polarizing means side with the display screen of the secondpolarizing means side being shielded, it is effective to suppress thelight transmitted to the second polarizing means side from thesemitransmission reflecting means from reflecting at random by theshielding body to re-enter the liquid crystal display device, and hencecolor oozing, image blurring and contrast lowering can be suppressed.

INDUSTRIAL APPLICABILITY

[0203] A double-side display type liquid crystal display capable ofdisplaying bright images of excellent display quality at both face andreverse sides is presented, and moreover display images can be visuallyrecognized in one liquid crystal display device both in the case where asecond main body is opened and in the case where closed.

1. A double-side display type liquid crystal display device comprising aliquid crystal, first and second electrodes for driving the liquidcrystal, first and second polarizing means disposed on both sides of theliquid crystal, a front light disposed at the opposite side of theliquid crystal of the first polarizing means, and semitransmissionreflecting means disposed at the second polarizing means side of theliquid crystal for passing a part of light from the front light sidepassing through the liquid crystal, wherein the first polarizing meansis optically disposed so as to absorb or transmit light passing throughthe liquid crystal, and the second polarizing means is opticallydisposed so as to absorb or transmit light passing through the liquidcrystal and then passing through the semitransmission reflecting means.2. The double-side display type liquid crystal display device of claim1, wherein the semitransmission reflecting means is a reflector disposedbetween the liquid crystal and the second polarizing means, and having atransmission window for passing a part of light from the front lightside passing through the liquid crystal.
 3. The double-side display typeliquid crystal display device of claim 2, wherein the first and secondelectrodes are transparent electrodes disposed between the liquidcrystal and first polarizing means and the liquid crystal and secondpolarizing means respectively, and the reflector having a transmissionwindow is disposed at the opposite side of the liquid crystal of thesecond electrode.
 4. The double-side display type liquid crystal displaydevice of claim 1, wherein the semitransmission reflecting means is areflection polarizer disposed between the liquid crystal and the secondpolarizing means, for reflecting light having a specified polarizingcharacteristic and passing all other light.
 5. The double-side displaytype liquid crystal display device of claim 4, wherein the devicefurther includes first and second glass substrates holding the liquidcrystal therebetween and disposed between the liquid crystal and thefirst and second polarizing means respectively; and a color filter ateither liquid crystal side of the first or second glass substrate, thereflection polarizer is adhered to the opposite side of the liquidcrystal of the second substrate; and the thickness of the secondsubstrate is 5 times or less of the narrowest width of the color filter.6. The double-side display type liquid crystal display device of claim1, wherein the device further includes a metal wiring electricallyconnected to the first electrode or second electrode, and a firstquarter λ phase difference plate is disposed between the metal wiringand first polarizing means when the metal wiring is located between theliquid crystal and the first polarizing means, or between the metalwiring and reflection polarizer when the metal wiring is located betweenthe liquid crystal and reflection polarizer.
 7. The double-side displaytype liquid crystal display device of claim 1, wherein the devicefurther includes a metal wiring electrically connected to the firstelectrode or second electrode, and a low reflection layer of lowerreflectivity of light than that of the metal wiring disposed at theopposite side of the liquid crystal of the metal wiring, the lowreflection layer being disposed optically closely in a shape after themetal wiring.
 8. An information appliance comprising a first main bodyhaving various operation switches, and a second main body having displaymeans for visually displaying various kinds of information, beingcoupled to the first main body in an opening and closing manner, whereinthe display means is a double-side display type liquid crystal displaydevice comprising a liquid crystal, first and second electrodes fordriving the liquid crystal, first and second polarizing means disposedon both sides of the liquid crystal, a front light disposed at theopposite side of the liquid crystal of the first polarizing means, andsemitransmission reflecting means disposed at the second polarizingmeans side of the liquid crystal for passing a part of light from thefront light side passing through the liquid crystal; windows aredisposed at the inner side of the casing and at the outer side thereofwhen the second main body is closed; the surface of the front light sideof the double-side display type liquid crystal display device isdisposed at one window; and the surface of the second polarizing meansside of the double-side display type liquid crystal display device isdisposed at the other window.
 9. The information appliance of claim 8,wherein the surface of the double-side display type liquid crystaldisplay device on the front light side is disposed at the windowprovided at the outer side of the second main body, and the surface ofthe double-side display type liquid crystal display device on the secondpolarizing means side is disposed at the window provided at the innerside.
 10. The information appliance of claim 9, wherein the appliancefurther includes opening/closing judging means for judging the openingor closing of the second main body, and a front light lighting switchwhich cooperates with the opening/closing judging means for lighting thefront light when the main body is judged to be opened.
 11. Theinformation appliance of claim 8, wherein the appliance further includeswriting direction inverting means for inverting the writing direction ofdisplay image data into each pixel of the double-side display typeliquid crystal display device in vertical or lateral direction.
 12. Theinformation appliance of claim 8, wherein the appliance further includesdata converting means for converting the data of display image into datainverted in vertical or lateral direction.
 13. The information applianceof claim 8, wherein the appliance further includes data converting meansfor converting the gradation of the data of display image.
 14. Theinformation appliance of claim 8, wherein the appliance further includesa second quarter λ phase difference plate disposed at the opposite sideof the liquid crystal of the second polarizing means of the double-sidedisplay type liquid crystal display device.